Since the discovery of thienamycin having a potential antimicrobial activity against Gram negative and Gram positive bacteria, studies on syntheses of carbapenem or penem derivatives which are analoguous to thienamycin have been widely developed.
The present inventors have conducted intensive investigations on syntheses of carbapenem or penem derivatives and, as a result, found that carbapenem or penem derivatives having, as their 2-side chain, a substituent easily derived from 4-hydroxy-proline, i.e., a substituted pyrrolidinyl group carrying a carbonyl group substituted with various substituents on its 2-position, exhibit potential antimicrobial activity and are useful as medicines or are important intermediates for compounds possessing antimicrobial activity, and thus completed the present invention.